Latrunculia (Biannulata) austini, Samaai & Gibbons & Kelly, 2006

Samaai, Toufiek, Gibbons, Mark J. & Kelly, Michelle, 2006, Revision of the genus Latrunculia du Bocage, 1869 Porifera: Demospongiae: Latrunculiidae) with descriptions of new species from New Caledonia and the Northeastern Pacific (, Zootaxa 1127 (1), pp. 1-71 : 46-48

Latrunculia (Biannulata) austini sp. nov.

( Figs 1O, 3H, 5D , 7 ; Tables 2 & 3)

Holotype material. Holotype 982­62­1 (Royal British Columbia Museum), Sutton Islands , Jervis Inlet, British Columbia, (49° 45.5'N 123° 55.6'W); depth 30 meters .

Other material. White Islets , Strait of Georgia, British Columbia, 5 specimens .

Description. Spherical sponge, 12 cm in diameter ( Fig. 3H). Surface smooth, velvety, with one large osculum, 10 mm in diameter, and numerous clusters of low flush areolate porefields 0.7–1 mm in diameter. Texture compressible, leathery and the ectosome is often largely missing giving the sponge a ragged appearance. The colour in life is brownish grey to purple brown; the sponge loses pigment in alcohol but remains dark. In formalin the pigment turns a purple colour.

Skeleton. The choanosomal skeleton is an irregular polygonal­meshed reticulation formed by wispy tracts of smooth styles with no distinction between the primary and secondary tracts ( Fig. 5D ). The tracts range in width from 90–120 m in thickness, and form meshes that are 100 m wide. In the deeper choanosome, tracts are robust and dense with no clear pattern, diverging in some areas towards the surface where the spicules tend to be vertically arranged and radiate in plumose tracts 150 m wide. Between the choanosomal layer and ectosome clear circular bands are visible, indicating an absence of megascleres in those regions. The surface of the ectosome is lined with a palisade of anisodiscorhabds. Beneath the ectosomal palisade is a thin dense paratangential layer of megascleres, approximately 50–150 m deep.

Spicules. Megascleres: styles are smooth, centrally thickened, fairly blunt, 376 (335–402) um x 9 (8–11) um, n=20. Microscleres ( Fig. 1O): anisodiscorhabds, the manubrium is poorly developed with irregular disposed quite long spines. The median whorl of distinct spines is broader than the subsidiary whorl that slants upwards and is microspined. The spines of the apical whorl are almost parallel with the axis, ending in a crown­like tuft of acute convex spines, 58 (51–64) m long.

Substrate, depth range and ecology. To date this species is only recorded for the Strait of Georgia to Jervis Inlet, British Columbia. This species is rather uncommonly encountered but can be locally abundant in certain localities, such as Skookumchuck Narrows, Vivian Islands and Sabine Channel, British Columbia. The live sponge has a noxious odour. Depth range from 20 to at least 50 m

Geographical distribution ( Fig. 7 ). British Columbia

Etymology. Name after Dr Bill Austin who collected this sample.

Remarks. Latrunculia austini sp. nov. is distinguished morphologically from other Latrunculia in that the surface of the sponge lacks the large cylindrical shaped oscules that are reported for most species. One large osculum is present, a character only ever recorded in L. basilis and L. millerae and the areolate porefields are made up of numerous clusters of low flush structures. In terms of spiculation, the megasclere dimensions are considerably smaller on average size than found in most Latrunculia species in the subgenus Biannulata , but the microscleres are larger and fall within the size categories as recorded for L. lunaviridis and L. microacanthoxea off the cold coastal upwelling waters of South Africa.

On average the subgenus Latrunculia have larger microscleres than the subgenus Biannulata and this is evident if we compare L. austini to L. basilis , L. bocagei , L. novaecaledoniae sp. nov. and L. biformis . The anisodiscorhabds of L. austini sp. nov also differ considerably from these other species within the subgenus Biannulata . The manubrium and apical whorl of L. austini is small and not as well developed as L. lunaviridis and L. triverticillata (see Fig. 1). The primary character that differentiates this species, however, is the form of the anisodiscorhabds, which has median­, subsidiary whorls and manubrium not well developed and on average the acanthodiscorhabd are larger than that for species within the subgenus Biannulata (see Table 3).

This is the second species to be recorded from 49°N in the Pacific Ocean, the only other being L. oparinae , but it is the first ever record to be found off British Columbia. L. oparinae has raised oscules as opposed to one large sunken oscules as found in L. austini sp. nov.. One of the key differences between these two species is that L. oparinae have styles that is terminally spined, a character that is lacking in L. austini sp. nov.. Apart from this, the anisodiscorhabd microsclere in L. austini sp. nov. is larger with a very ill­formed manubrium.

Figures

FIGURE 5. Photomicrographs of choanosomal architectures: A. Latrunculia ikematsui Tanita 1968; B. Latrunculia oxydiscorhabda Alvarez et al. 2002; C. Latrunculia triverticillata Alvarez et al. 2002; D. Latrunculia austini sp. nov.; E. Latrunculia citharistae Vacelet 1969; F. Latrunculia purpurea Carter 1881.

FIGURE 7. Worldwide distributions of Latrunculia (Biannulata) species. Distributions of A) Latrunculia spinispiraefera Brøndsted, B) Latrunculia citharistae Vacelet, C) Latrunculia purpurea Carter, D) Latrunculia oparinae Samaai and Krasokhin; E) Latrunculia lunaviridis Samaai and Kelly; F) Latrunculia microacanthoxea Samaai and Kelly; G) Latrunculia kaakaariki Alvarez et al.; H) Latrunculia duckworthi Alvarez et al.; I) Latrunculia procumbens Alvarez et al.; J) Latrunculia wellingtonensis Alvarez et al., 2002; K) Latrunculia kaikoura Alvarez et al.; L) Latrunculia millerae Alvarez et al.; M). Latrunculia austini sp. nov.